1. Field of the Invention
Embodiments of the invention are generally directed to the field of remote sensing and surveillance. More particularly, embodiments of the invention are directed to an unmanned air vehicle (UAV) system and a small unmanned air vehicle (SUAV) system for deploying and towing a sensor in a tow medium, and to methods related thereto.
2. Description of Related Art
Remote sensing and surveillance have many applications. The particular field of applications addressed by the embodiments of the invention relate to the towing of a tethered sensor system (tow body) through an atmospheric or an underwater tow medium by a tow vehicle. In a typical example, an active or passive SONAR-based sensor is attached to a tow line that may be attached to a water surface vessel. The sensor is dragged through the water to sense submerged and/or waterborne objects or to map the floor of the water body, for example. An exemplary tactical application of such sensing is tracking a submerged submarine. In this scenario, however, the use of a waterborne tow vessel becomes impractical. Although a ship has the power and thrust capacity to tow a submerged tow body at a desired speed and general direction, the resources and energy consumption are costly. Furthermore, the intended target will not likely be anywhere near the surface vessel, and the surface vessel will not be able to travel to the intended surveillance location in a timely manner.
To overcome these and other challenges, rotary winged aircraft have been typically employed as tow vehicles. Rotary winged aircraft are advantageous in that they can be dispatched relatively quickly and, by their nature, can hover for accurate deployment of a tow body. In addition, they are particularly suited to the relatively static towing constraints of dipped or submerged sensors, as well as those of, e.g., chemical-biological-radiological-nuclear (CBRN) sensors or other tactical atmospheric or local environment sensors.
Disadvantageously, however, rotary winged aircraft normally used with the above-mentioned sensor deployment and towing maneuvers have relatively limited range, endurance and payload capacity compared to a fixed wing aircraft such as an autonomous unmanned air vehicle (UAV) or a small autonomous unmanned air vehicle (SUAV), for instance.
In contrast to rotary winged aircraft, fixed wing aircraft generally require continuous and relatively high airspeeds to operate without stalling and ultimately crashing. Thus fixed wing aircraft are not normally associated with the static towing maneuvers and deployment requirements of local surveillance sensors, CBRN sensors, submerged SONAR tow bodies and the like.
The inventors have recognized, however, the many advantages of using a UAV or an SUAV as the tow vehicle for the types of tow bodies and sensor applications referred to above. These advantages include, but are not limited to, low cost, high endurance, quick dispatch, large payload capacity, long persistence sensing, long range delivery and mission adaptability. There is thus a recognized need for UAV and/or SUAV systems for deploying and towing air or water-based sensors flown in a manner to maintain airspeeds necessary for continuous flight while flexibly managing tow position and tow velocities relative to the earth's surface.
These advantages and benefits as well as others will become more evident to persons skilled in the art in view of the following description and drawings.